The moveable contacts carried by moveable contact pieces of electric switches are required to move quickly into contact with and away from the fixed contacts because an indeterminate state of contact between a fixed contact and a moveable contact often causes undesirable generation of heat particularly when an inductive load is involved. To produce such a desired quick motion of moveable contact pieces, electric switches are often provided with snap springs which change the directions of their action upon moveable contact pieces in a desired manner depending on the state of the manual actuator.
Since an electric switch using a snap spring involves a toggle action, a considerable force is required to be produced by the snap spring and considerable strain is produced in the snap spring. Therefore, ensuring the durability of the snap spring is a major task in designing a small electric switch using a snap spring.